I, too, live in NC, and as for the front plate, it may be a good idea to mention it just to be sure, but I can tell you that I didn't worry about it for either one. Not only did they NOT drill holes for a front bracket, I never even received the brackets for either car! I am not sure if that is an NC car thing or not, that's why I say if you are anal about that kind of thing you may wish to mention it.
I think it must depend on the dealer and whether they order them. My state is rear-plate-only, too, and I don't ever recall seeing a new Mustang at my local dealer that had the bracket installed. However, when I was searching online for my car, the downloadable window stickers from a different dealer in a nearby city listed the bracket as a NO CHARGE option on every single car they had in stock or on order.
My suggestion, then, is to be safe rather than sorry ... because once those holes are there, they're there.